Outcomes, Safety And Efficacy Of Descemet Membrane Endothelial Keratoplasty (Dmek) When Leaving A Complete Air Tamponade And Abandoning 'Waiting Time' At The End Of Surgery

A 100% air tamponade in the anterior chamber (AC) for about 30-60 minutes at the end of standard Descemet Membrane Endothelial Keratoplasty (DMEK) is known as 'waiting time' and should promote donor graft adherence to the recipient’s corneal stroma. A subsequent air/fluid exchange reduces the air tamponade to 30-50% to avoid postoperative complications such as a pupillary block or intraocular pressure (IOP) elevation. Abandoning the 'waiting time' will result in a shorter total surgery time. We investigated the clinical outcomes after DMEK, as well as intraoperative anesthesiological parameters in a large patient cohort without 'waiting time' and without air/fluid exchange and compared the results to a matched control group.

Retrospective analysis at a tertiary reference center in Germany.

In total, 50 eyes of 50 patients (female=34; male=16) were included who underwent DMEK under general or topical anesthesia without 'waiting time' and without subsequent air/fluid exchange. Those were compared to a matched control group (age, gender, diagnosis, surgery, anesthesia) of 50 eyes that had received standard DMEK with 'waiting time' and air/fluid exchange. In the study group, air was released from the AC at the slit-lamp in the event of a pupillary block or increased IOP. The patients were monitored for signs of infection and graft detachment up to 6 months postoperatively. Anesthesiological parameters were collected intraoperatively and analysed in terms of patient safety and complications.

DMEK was performed under general (n=41) or topical anesthesia (n=9) as a stand-alone procedure in pseudophakic (n=27) or phakic eyes (n=4) or was combined with cataract surgery (n=19). Preoperative diagnoses were Fuchs Dystrophy (n=41), (pseudophakic) bullous keratopathy (n=5), or transplant failure (n=4).

AC deflation was required  due to a pupillary block (n=13) or a deep AC with (n=7) or without (n=7) IOP elevation. No intraocular inflammation occured during the study period. Visual acuity and pachymetry improved in all patients. Four eyes needed rebubbling for graft detachment (8%). Clinical outcomes of the study group were comparable to the control group and less intraoperatively administered systemic anesthetics were required.

DMEK without an air/fluid exchange at the end of surgery increases the risk of pupillary block or IOP elevation. Both can be resolved by timely air removal at the slit-lamp on the surgery day without inducing an intraocular infection. The shorter DMEK surgery time consequently reduces the duration of general anesthesia and its associated risks and complications. Moreover, this strategy allows a more efficient utilization of operation room facilities and capacities.